Thermal switch having a pivotally mounted temperature responsive member with a lateral portion for translating a movable switch actuator



Jan. 3, 1967 BAAK 3,293,401

THERMAL SWITCH HAVING A PIVOTALLY MOUNTED TEMPERATURE RESPONSIVE MEMBER WITH A LATERAL PORTION FOR TRANSLATING A MOVABLE SWITCH ACTUATOR Filed Aug. 31, 1964 Fza , 46', 3 4 44 35 37 T. "IETIIfITI I I 5 /4 39 40 Z A 37 M .P 34 c 3 2 16.4. Z4 /2 3 2 25] 0 1.. J

M/VEA/TOQ ALBEQTEBAAK 5y H/S ATTDZA/EYS HAQQ/S K/ECH, RUSSELL 6c KER/v United States Patent 3,296,401 THERMAL SWITCH HAVING A PIVOTALLY MOUNTED TEMPERATURE RESPONSIVE MEMBER WITH A LATERAL PORTION FOR TRANSLATING A MOVABLE SWITCH AC- TUATOR Albert E. Baak, 640 Ocampo Drive, Pacific Palisades, Calif. 90272 Filed Aug. 31, 1964, Ser. No. 393,079 3 Claims. (Cl. 200-138) Control switches which are responsive to temperature changes have utility in many diiferent combinations. For example, a thermostatically actuated control switch may be located in the hot air stream discharging from a furnace. If the air temperature rises above a predetermined maximum temperature, the switch may function to shut down the furnace and, optionally, to sound a warning buzzer or to turn on a light to indicate that the furnace has been shut down. Control switches typically comprise a housing which may include several sections with at least two contacts therein and a moving blade or conductor means to connect and disconnect the contacts. Means responsive to changes in temperature are also provided to move the blade to either connect or disconnect the contacts.

Switches of this general type are well known and widely used. -It is an object of the present invention to provide a new and improved switch providing better performance and simpler and more reliable operation.

It is an object of this invention to provide simple means for connecting sections of the switch housing together. Another object of this invention is to provide simple means on the internal conductors of the switch for connecting together the various housing sections. An additional object is to provide such a switch structure utilizing the same means for holding the conductors within the housing and holding the housing sections together.

A further object of this invention is to provide a control switch having improved temperature responsive means for actuating the switch. Still another object of this invention is to provide a control switch having means for causing an arm, which engages a conductor within the switch, to reciprocate to connect and disconnect a set of contacts within the switch.

The objects of this invention may be realized by providing a housing having at least two sections and a plurality of conductive contacts within the housing. A plurality of cars is formed on each contact carrying conductor and some of the ears extend into one of the housing sections and other of the ears extend into another of the housing sections. By appropriately bending these ears, which are integral with the conductors, the housing sections can be quickly and tightly secured together.

Another aspect of the invention is the novel means for providing reciprocation of an arm which is used to open and close the control switch. In one form, the means for causing reciprocation comprises a bimetallic strip disposed at an angle with respect to the arm so that deflections of the bimetallic strip cause the arm to reciprocate. In another form, the arm is connected to and caused to reciprocate by a bimetallic strip bent to conform to the shape of a bell crank, permitting the use of a relatively long and thin temperature sensing structure for projecting into a ductor other structure through a relatively small opening.

The invention also comprises novel details of construction and novel combinations and arrangements of parts, which will more fully appear in the course of the following description. The drawing merely shows and "ice the description merely describes preferred embodiments invention;

FIG. 2 is an enlarged sectional view taken along line 22 of FIG. 3 showing the preferred embodiment of the control switch of the present invention;

FIG. 3 is a partial sectional view taken along line 33 of FIG. 2;

FIG. 4 is a sectional View taken along line 4-4 of FIG. 2 showing means for securing the several housing sections together;

' FIG. 5 is a partial sectional view showing a manual reset button which is useable with the control switches of this invention;

FIG. 6 is a sectional view of another embodiment of the invention; and 1 FIG. 7 is a plan view of a portion of one of the conductors of the switch.

In FIG. 1, a housing 1 comprising a first housing section 3 and a second housing section 5 is secured by a mounting bracket 7 to a plate 9. Protruding from the housing 1 from separate terminal openings is a plurality of terminals 10, 11 and 12 for connecting the various switch contacts into any desired circuit. A plurality of counterbores 13 is provided in each of the housing sectiones 3, 5 for a purpose which is described hereinafter. A channel-shaped support 14 is attached to the rear of the plate 9 by any suitable means such as rivets 15. Holes 13' through the housing sections provide an alternative mounting.

The details of construction of the preferred embodiment may best be viewed with reference to FIG. 2. The housing 1, which is preferably constructed of plas tic or other suitable insulating material, supports a first fixed contact carrying conductor 16, a second fixed contact carrying conductor 17, and another conductor 18. Threadedly secured to the conductor 16 is a contact screw 19 having a fixed contact 20. The conductor 17 has a fixed contact 21. The conductor 18 has a blade 27 carrying a moving contact 28 and fixed to the conductor 18 by a rivet 22. The conductors 16, 17, 18 have portions which extend outside of the housing to form the terminals 11, 12 and 10 respectively and each is preferably formed from a single sheet of conductive metal.

Each of the conductors 16, 17 and 18 is provided with widened portions forming a plurality of cars 24, as

shown in FIGS. 4 and 7, for joining the two housing sections together and holding the conductors in place in the housing. A pair of the cars 24 on a conductor may extend through a slot or bore 25 into one of the counterbores 13 in the housing section 3 and another pair of the ears on that conductor may extend through an opposing slot or bore 25 into one of the counterbores 13 in the housing section 5. In the specific embodiment illustrated, the conductor 18 is provided with four ears, two of which extend into the housing section 3 and the remaining two extend into the housing section 5. By inserting an appropriate tool into each of the counterbores 13 the cars 24 may be twisted or bent so as to secure the housing sections 3 and 5 together and to secure the conductor to the housing. Portions of the interior walls of the housing sections 3, 5 are closely adjacent the conductors 16, 17, 18 as shown tofurther secure the conductors in the housing 1.

A moving contact carrier in the form of a spring biased blade 27 is provided for connecting and disconnecting the contacts 20, 21, and 28. The blade 27 carrying the contact 28 is normally biased into engagement with the contact 20 by a curved resilient spring 29 which is preferably integral with the blade 27. The spring 29 is held in the curved compressed position shown in FIG. 2 by a V- shaped notch 30 in a rigidly mounted element 31 which is preferably a lateral extension of the conductor 18. It should be understood that the blade 27 could be normally biased into engagement with the contact 21 of the con ductor 17 if desired.

Means responsive to temperature change are provided to move the blade 27 from the contact 20 to the contact 21. The channel-shaped support 14 includes apertured dimples 34 and has a temperature responsive bimetallic element 35 secured thereto by a bolt 37 and a pin 39 which extends through the apertures in the dimple. The bimetallic element 35 extends in one direction for a first portion of its length 40 and in another direction for a second portion of its length 41 to form a substantially bell-crank-shaped element pivotally mounted to the channel-shaped support 14 by the pin 39. The bimetallic strip 35 comprises two metal layers having dissimilar coefficients of expansion and secured together in accordance with conventional practice. It is apparent that by positioning the metal which would expand more rapidly on the outside, the portion 41 of the bimetallic strip would move clockwise as seen in FIG. 2 as the temperature increased. Conversely, by positioning the metal which would expand more rapidly on the inside of the bell crank, the portion of the bimetallic element 41 would move counterclockwise as seen in FIG. 2 as the temperature increased, which is the arrangement utilized in the particular embodiment illustrated. A push rod in the form of an elongated flat member 43 having a reduced end portion 44 to define a shoulder 45 is provided to transfer the motion of the portion 41 of the bimetallic element to the blade 27. The reduced end portion 44 is inserted through an aperture 46 in the bimetallic element and the shoulder 45 bears laterally against the portion 41 of the bimetallic element. If desired, the end portion 44 may be secured within the aperture 46 by providing suitable interengaging grooves or by employing bonding. Normally the member 43 merely floats in the aperture 46.

Reciprocating motion of the member 43 is transmitted to an arm 47 which is secured to the member 43 by any suitable means such as rivets 48. The arm 47 passes through an aperture 49 in the housing and an opening 50 in the conductor 18 to engage the blade 27.

Optionally, the channel-shaped support 14 may be provided with several apertured dimples 34 along its length through which the pin 39 may be inserted and various lengths may be chosen for the support. This allows flexibility in the selection of the 'length of the bell-crankshaped bimetallic element. The position of the bell crank bimetallic element and hence the temperature at which the switch is actuated, may be adjusted by turning the bolt 37 either upwardly or downwardly.

The operation of the control switch is as follows. In the position shown in FIG. 2, the blade 27 has been snapped to the left by the force exerted by the heated bimetal to complete a circuit through contacts 21 and 28. As the temperature at the bimetal decreases, the portion 41 of the bimetallic element 35 moves to the right, permitting the member 43 and arm 47 to move a corresponding distance to the right. When the push rod member 43 moves a sufficient distance to the right, the spring 29 will snap the blade 27 to the right to complete a circuit through contacts 20 and 28. When the temperature of the bimetal increases, the reverse occurs. The portion 41 of the bimetallic element 35 moves to the left and, after it has moved a predetermined distance, the force exerted by the push rod will be sufiicient to snap the blade 27 into eng'agement with the contact 21.

, Either of the fixed contacts 20, 21 and associated conductor may be omitted if desired or merely not used if not needed. Various forms of resilient members other than leaf spring 29 may be used to bias the blade 27, and

the support 14 need not be channel-shaped as shown. The contact screw 19 adds flexibility to the switch by providing convenient means to adjust the position of the blade when in the right position and thereby provide an adjustment for the amount of bimetal movement required for switch actuation.

FIG. 5 shows an alternative form of the switch of the present invention including a manual reset button. The device of FIG. 5 is the same as that shown in FIG. 2 except that the conductor 17 has been replaced by a reset button 53 and spring 56. Also, the terminal of the conductor 16 exits through the upper portion of the housing section 3 to form a terminal 11.

The reset button 53 has a stepped stern portion 54 mounted in a correspondingly stepped bore 55 of the housing section 3. The reset button 53 is urged outwardly by a bent metallic washer 56 which surrounds the stem 54.

In the embodiment of FIG. 5, a temperature change causes the arm 47 to move toward the left as seen in FIG. 5, to ultimately snap the blade to the left and open the circuit at contacts 20, 28. Should the temperature trend now reverse so that the arm 47 can move back toward the right, the blade 27 will not accompany it, because the spring 29 is not adjusted to normally snap the blade to the right. The switch must be manually closed by pushing the reset button 53 to the right to engage the upper portion of the blade 27 to cause it to move and subse- 4 quently snap into engagement with the conductor 16 under the force of spring 29. The embodiment shown in FIG. 5 has particular utility in a combination in which the opening of the switch causes a shutdown which should be observed by an operator prior to restarting.

The embodiment shown in FIG. 6 is the same as that shown in FIG. 2 except that the means responsive to temperature change for causing the arm member to reciprocate to move the blade 27 have been changed. In FIG. 6, the terminal 12' of the conductor 17 is also shown as exiting from the top portion of the housing section 3. It should be understood, however, that the terminals 10, 11 and 12 may protrude from any suitable surface of the housing sections 3 and 5.

As shown in FIG. 6, a bimetallic element 60 is mounted within a recess in the housing 1. The element 60, which is a substantially straight flat strip, is restrained at one end by a screw 61 and is pivotally secured at the other end by a hook 62 formed in the element which engages a projection 63 of the housing 1. As in the previous embodiment, the arm 47, which extends transversely of the element 60, passes through housing opening 49 and engages the bimetallic element at one end and the blade 27 at the other end.

It should be understood that by proper positioning of the two metals in bimetallic element 60, the element may be made to flex either toward or away from the housing by a temperature increase, to provide any desired switch action. The operation of the embodiment shown in FIG. 6 is the same as that shown in FIG. 2.

It is apparent that the reset button shown in FIG. 5 may be used with the embodiment shown in FIG. -6. Also, the housing sections of the embodiment shown in FIG. 6 may be secured together by the ears 24 on the conductors 16, 17, 18 as shown in FIG. 4. The switch may be utilized independently of the mounting plate 9 if desired.

Although exemplary embodiments of the invention have been disclosed and discussed, it will be understood that other applications of the invention are possible and that the embodiments disclosed may be subjected to various changes, modifications and substitutions without necessarily departing from the spirit of the invention.

I claim as my invention:

1. In a temperature responsive electric switch, the combination of:

a switch housing carrying a switch unit;

a support member joined to said housing and projecting from said housing along a path;

a movable member disposed along said path and extending into said housing for actuating said switch unit;

a temperature responsive member having a longitudinal portion and a lateral portion joined together adjacent the inner ends thereof;

means for pivotally mounting said temperature responsive member on said support member with the longitudinal portion extending in the direction of said path and with the lateral portion engaging said movable member in driving relation with flexing of said temperature responsive member producing translation of said movable member and operation of said switch unit; and

means for fixing the distance between the outer end of said lonigtudinal portion and said support member.

2. A combination as defined in claim 1 wherein said last-mentioned means includes a threaded member interconnecting said outer end of said longitudinal portion and said support member, said threaded member being rotatable to adjust the distance between the outer end of said longitudinal portion and said support member to thereby References Cited by the Examiner UNITED STATES PATENTS 2,582,131 1/1952 Jorgensen et al 200166 2,715,167 8/1955 Mertler 200138 2,826,072 3/1958 Kliever 200138 X 2,891,128 6/1959 Bolesky 200-138 2,945,098 7/1960 Ludwig 200-466 X 3,081,388 3/1963 Cox 200138 3,155,799 11/1964 Mitick 200-138 BERNARD A. GILHEANY, Primary Examiner.

T. MACBLAIN, H. A. LEWITTER,

Assistant Examiners. 

1. IN A TEMPERATURE RESPONSIVE ELECTRIC SWITCH, THE COMBINATION OF: A SWITCH HOUSING CARRYING A SWITCH UNIT; A SUPPORT MEMBER JOINED TO SAID HOUSING AND PROJECTING FROM SAID HOUSING ALONG A PATH; A MOVABLE MEMBER DISPOSED ALONG SAID PATH AND EXTENDING INTO SAID HOUSING FOR ACTUATING SAID SWITCH UNIT; A TEMPERATURE RESPONSIVE MEMBER HAVING A LONGITUDINAL PORTION AND A LATERAL PORTION JOINED TOGETHER ADJACENT THE INNER ENDS THEREOF; MEANS FOR PIVOTALLY MOUNTING SAID TEMPERATURE RESPONSIVE MEMBER ON SAID SUPPORT MEMBER WITH THE LONGITUDINAL PORTION EXTENDING IN THE DIRECTION OF SAID PATH AND WITH THE LATERAL PORTION ENGAGING SAID MOVABLE MEMBER IN DRIVING RELATION WITH FLEXING OF SAID TEMPERATURE RESPONSIVE MEMBER PRODUCING TRANSLATION OF SAID MOVABLE MEMBER AND OPERATION OF SAID SWITCH UNIT; AND MEANS FOR FIXING THE DISTANCE BETWEEN THE OUTER END OF SAID LONGITUDINAL PORTION AND SAID SUPPORT MEMBER. 